A few machines can work on one field - you just have to be careful so they don't block each other
In Farming Simulator you only need three steps that will prepare your field for any type of crops or vegetables. First you must drive a cultivator and then a planter machine (only potatoes requires a different machine than the default one). Both types of machines have their upgraded versions that generates more resistance (requires a better tractor to use its full potential). Fertilizing increases your crops by 30% but it has no impact on crops' growth speed. You can use an artificial fertilizer (first, you must fill a tank, it costs about 2800$ and it can be used to fertilize one of the smaller fields) or a natural - deliver grass/chaffs/straws to biogas installation or give straw to your cows/pigs and the animals will produce natural fertilizer. It is worth to know that you can fertilize meadows. Each stage of growth of every plant takes about 10 minutes so in order to get your crops you must wait about 30-45 minutes.
Finally, when your plants are fully grown (their color will be gold/brown), you can collect them by using a combine. Notice, that the default reel can only be used to collect wheat and rapeseed. Corn and sunflowers require a different reel (you can purchase it in a shop, available for all types of combines). Only potatoes and beetroots require a special combine which is attached to a tractor. A forage harvester is an alternative option for collecting crops - you can get chaffs from corn that can be placed in silos in biogas installation and made into silage and getting natural fertilizer.